It is known to provide high intensity dimmable light-emitting diode (LED) luminaires for use in both indoor and outdoor spaces. On such LED luminaire is described in US-A-2012/0033400 for use as emergency ballast for car parks. The luminaire can have either a fixed output or a dimmable output and incorporates a movement sensor which can be used to change the illumination status of the luminaire. In addition, different turn-off schemes are described including a progressive turn-off with soft transitions between lighting levels.
In addition, it is known to use a light sensor in luminaires in a night mode operation. One such luminaire is described in GB-A-2459180 where a light sensor is incorporated into a luminaire system having a movement sensor and an adjuster for adjusting the output from the luminaire in accordance with sensed movement and/or sensed light levels.
Another lighting system that includes both presence detection and light level detection is described in EP-A-0447136. A dimmable electronic ballast is connected to a presence detector and a light detector to control its operation in accordance with conditions in a localised area associated with the dimmable electronic ballast.
With the requirement for more efficient, more environmentally friendly lighting systems, NEMA photocell sockets are used, together with NEMA photocells, to control the switching on and switching off of associated luminaires in accordance with ambient lighting conditions. [NEMA refers to the National Electrical Manufacturers Association and is a trade association for the electrical manufacturing industry whose member companies manufacture products used in the generation, transmission and distribution, control and end-use of electricity.] However, such systems are not readily dimmable without the modification, and, in particular, extra wires need to be provided between the photocell and a controller within the socket.